First evidence of oncologic neuropathic pain prevalence after screening 8615 cancer patients. Results of the On study

Background: Thirty percent to ninety percent of cancer patients suffer from pain, including neuropathic pain (NP), which results in great burden for cancer patients. Thus, it was of great interest to determine NP prevalence in cancer patients in Spain, to raise awareness of the condition, and aiming to improve management of cancer NP. Patients and methods: A 1-month follow-up prospective epidemiological multicenter study was conducted to assess prevalence and management of NP in Spanish oncologic units. The first 10 cancer patients at each unit diagnosed with NP by the validated Douleur Neuropathique 4 questionnaire (DN4) were recruited. Results: Of 8615 screened patients, 2567 (30%) suffered from pain. From these, 33% had NP according to investigators and 19% according to DN4 test. Three hundred and sixty-six patients (mean age 62.6 years; 61.2% male) were recruited. Pain decrease at 1 month was greater in patients with metastases (P < 0.01) and depended on treatment (P < 0.05), with 'oxycodone' showing 50.4% pain relief. Conclusions: NP prevalence in cancer pain is 33%. DN4 reports only about half the cancer NP cases diagnosed by clinicians. Pharmaceutical treatment of cancer pain, including NP, has a greater effect in patients with metastases and seems to depend on the specific treatment used.